RU2275489C2 - Hydromechanical centralizer - Google Patents

Abstract

FIELD: well drilling, particularly hole clearance cementing, namely for casing pipe cementing in well.

SUBSTANCE: centralizer comprises cylinder connected with bore and provided with bushes and working piston arranged in cylinder interior. The piston is fixed relative cylinder by shear pin. Centralizer also has valve bush, centering levers pivotally connected to bore by lower ends thereof, lock means. Three bushes are made as semi-bushes connected one with another in pairs by pins. Lock means are created as T-shaped slots made on lower part of working piston and brought into cooperation with T-shaped pins fixedly secured to centering arms. Valve bush is installed in cylinder interior above semi-bushes. Outer bush diameter is less than inner cylinder diameter. Outer surface of lower working piston part is made as a cone to cooperate with conical surfaces made in upper parts of centering levers. Working piston is made as semi-pistons fixedly secured one to another in conical parts. Threaded radial orifice is formed in bore to communicate inner cavities of cylinder and bore. Breakable plug is screwed into the threaded orifice.

EFFECT: increased operational reliability and simplified structure thereof.

3 cl, 5 dwg

Description

The invention relates to the field of cementing the annulus of a casing string, namely, cementing a casing string in a well.

A well-known casing centralizer, including a barrel with a sleeve screwed onto it, with which a cylinder is rigidly connected, in the cavity of which there are bushings with the ability to interact with each other by wedge-shaped surfaces, fixed with pins, working and locking pistons, centering levers and locking devices. The spool sleeve is installed in the cavity of the coupling to block the channel connecting the cavity of the cylinder with the internal cavities of the coupling and the barrel. The working and locking pistons are mounted with the possibility of moving in one direction and are fixed relative to the cylinder with a shear pin, the working piston having grooves on the outside and the locking piston, the length of which exceeds the working length, is connected to the centering levers by means of locking devices and has a wedge-shaped surface for interaction with one of the ends of the centering levers, the other ends of which are pivotally connected to the barrel, the locking devices are made in the form of a T-shaped groove in the locks m and piston pins mounted to their fixing to the levers, the upper ends of which rest against the working piston end (Pat RF №2191881, 21 cl E 17/10, published in Bulletin №30 -..... 27.10.2002).

The main disadvantages of this device are the design complexity and the unreliability of its operation.

Before building up the casing pipe onto the casing string while the latter is being lowered into the well, it is wedged, which creates a large acceleration, i.e. the column stops abruptly. In this case, there is a high probability of premature opening of the channel connecting the cylinder cavity with the internal cavities of the coupling and the barrel.

During the intermediate flushing of the well, it is likely that the casing centralizer will operate, which will not allow the casing to be lowered to a predetermined depth.

The use of integral sleeves and integral working and locking pistons in the cylinder cavity makes it possible to jam them when the casing centralizer is triggered.

The strength of the cylinder compared to the barrel for overpressure even with the same wall thickness is less, because the average barrel diameter is smaller than the average cylinder diameter. This is due to the fact that the outer diameter of the casing centralizer is limited by the diameter of the well, and the inner diameter of the barrel and sleeve by the inner diameter of the casing. The use of this centralizer in casing rigging will not allow hydraulic fracturing of productive strata of a well, as during hydraulic fracturing, the overpressure at the wellhead reaches up to 70 MPa.

The implementation of the locking device in the form of a T-shaped groove in the locking piston and pins installed to fix them in the centering levers, the upper ends of which abut against the end face of the working piston, leads the pins to cut. Since the allowable shear stress is much less than the allowable tensile stress ([τ] ≈0.5 [σ]) for plastic material, the likelihood of a premature actuation of the centralizer when the casing is lowered into the well increases.

The presence in the design of the casing centralizer of the locking piston having wedge-shaped surfaces in the lower part for interacting with one of the ends of the centering levers and T-shaped grooves, bushings with the possibility of interaction between each other with wedge-shaped surfaces, fixed by pins, and a coupling with a channel that is complex in the profile connecting the cylinder cavity with the internal cavities of the coupling and the barrel complicate the design of the centralizer.

A hydromechanical centralizer is proposed, including a cylinder connected to the barrel, in the cavity of which there are bushings and a working piston, fixed relative to the cylinder by a shear pin, spool sleeve, centering levers, lower ends pivotally connected to the barrel, locking devices. Bushings in the amount of 3 pieces are made in the form of half-sleeves, interconnected in pairs with dowels. The locking devices are made in the form of T-grooves on the lower part of the working piston, interacting with T-pins, rigidly fastened to the centering levers. The spool sleeve is mounted in the cylinder cavity above the half-bushings, the outer diameter of the sleeve being smaller than the inner diameter of the cylinder. The outer surface of the lower part of the working piston is made in the form of a cone for interacting with the conical surface of the centering levers made on their upper part, and the working piston is made in the form of a half-piston, rigidly fastened to each other in the conical part. A threaded radial hole is made in the barrel, connecting the internal cavities of the cylinder and the barrel, into which a destructible plug is screwed. The upper part of the inner cavity of the cylinder is made in the form of a cone for interaction with the outer conical surface of the spool sleeve, the latter having a radial hole made below the conical surface. The outer diameter of the barrel in the upper part under the spool sleeve is larger than the outer diameter of its lower part, and the radial hole is located with the possibility of overlapping its spool sleeve after the centralizer is activated.

The present invention solves the following tasks.

Improving the reliability of the hydromechanical centralizer by installing 3 pieces in the design of bushings made in the form of half-sleeves connected in pairs by dowels, making the locking device in the form of T-grooves on the bottom of the working piston, interacting with T-shaped pins, is rigid fastened with centering levers, setting the spool sleeve in the cylinder cavity above the half bushings, the outer diameter of the sleeve being smaller than the inner diameter of the cylinder, making the outer surface n the bottom of the working piston in the form of a cone for interacting with the conical surface of the centering levers made on their upper part, the working piston made in the form of a half-piston, rigidly fastened together in the conical part, making a radial hole with a thread in the barrel connecting the internal cavities of the cylinder and the barrel into which the destructible plug is screwed, the top of the inner cavity of the cylinder in the form of a cone for interacting with the outer conical surface of the spool sleeve, and the latter has a radial hole made below the conical surface, the outer diameter of the barrel in the upper part under the spool sleeve is larger than the outer diameter of its lower part, and the radial hole is arranged to overlap it with the spool sleeve after the centralizer is activated.

The installation in the cavity of the cylinder of half-shells in the amount of 3 pieces, interconnected by dowels, and a working piston made in the form of a half-piston, rigidly fastened to each other in the lower conical part, eliminates the likelihood of them jamming during the operation of the hydromechanical centralizer.

The implementation of locking devices in the form of T-grooves on the lower part of the working piston, interacting with T-shaped pins, rigidly fastened with centering levers, creates breaking forces on the T-shaped pins in cases of centering levers of the centralizer of the hydromechanical cavern during casing tripping operations columns in the well, which reduces the likelihood of premature centralizer operation in the well conditions.

Installing a spool sleeve with the possibility of overlapping a radial hole of the barrel having an outer diameter smaller than the inner diameter of the cylinder, a conical outer surface in the upper part and a radial hole made below the conical surface, in the cylinder cavity the upper part of the inner cavity of which is made in the form of a cone for interacting with the outer conical the surface of the spool sleeve makes it possible to increase the structural strength of the hydromechanical centralizer to excessive internal pressure e after actuation of the centralizer in a downhole environment.

The installation of destructible plugs in the radial threaded hole made in the barrel eliminates the premature actuation of the hydromechanical centralizer when the casing is lowered into the well and intermediate flushing of the wellbore.

The implementation of the outer diameter of the barrel in the upper part under the spool sleeve is larger than the outer diameter of its lower part, and the radial hole with a thread in the barrel with the possibility of overlapping it with the spool sleeve after the centralizer operates, ensures the operability of the hydromechanical centralizer in well conditions.

Simplification of the design of the hydromechanical centralizer due to the exclusion of the lock piston from the design, which has wedge-shaped surfaces at the bottom for interacting with one of the ends of the centering levers and T-grooves, couplings with a complex profile channel connecting the cylinder cavity with the internal cavities of the coupling and the barrel, replacing cavity of the cylinder of the bushings with the possibility of interaction between each other by wedge-shaped surfaces fixed between each other by pins on the bushings in the amount of 3 pieces, made in the form of half-sleeves and with knitted together in pairs by dowels, changes in the design of locking devices made in the form of T-grooves on the bottom of the working piston, interacting with T-shaped pins, rigidly fastened with centering levers and replacing the channel of a complex profile connecting the cavity of the hydraulic cylinder with the internal cavities of the coupling and the barrel, onto a radial threaded hole made in the barrel and connecting the internal cavities of the cylinder and the barrel.

Figure 1 shows the centralizer hydromechanical, axial section; figure 2 shows a section aa, figure 3 is a section bb, figure 4 is a section bb, figure 5 is a section gg.

The hydromechanical centralizer (Fig. 1) consists of a barrel 1 with a cylinder 2 screwed on it. Inside the cylinder 2, a spool sleeve 3, half-bush 4, interconnected by dowels 5, protective rings 6, rubber o-rings 7 and a working piston 8 made in half-piston, rigidly interconnected on a conical surface. On the lower part of the working piston 8, T-grooves 9 are made, interacting with the T-shaped pins 10. The pins 10 are rigidly fixed to the upper ends of the centering levers 11. The lower ends of the centering levers 11 are pivotally mounted in the lock nut 12. On the barrel 1 there is a radial a threaded hole 13 into which a destructible plug 14 is screwed. On the spool sleeve 3 there is a radial hole 15 located below the conical surface. The working piston 8 is fixed relative to the cylinder 2 with a shearing pin 16.

The hydromechanical centralizer operates as follows.

After the casing is lowered into the well, together with the hydromechanical centralizers installed under it, a cement plug is moved up and down, passing through the centralizer, destroys the collapsible plug 14 screwed into the radial hole 13 with a thread. After that, through the radial hole 13, the intra-column fluid is opened into the cavity of the cylinder 2. Under the action of the differential pressure of the annular and intra-column fluids, the spool sleeve 3, half-bush 4 connected by dowels 5, protective rings 6, rubber o-rings 7 and the working piston 8 will move down by cutting off the cutting pin 16. During the downward movement of the working piston 8, the centering levers 11 move in the radial direction. Upon reaching the centering levers 11 of the walls of the well, the casing is centered relative to the well. In the process of reducing the pressure in the inner cavity of the casing string under the action of a pressure differential due to the difference in the densities of the annular and annular fluids, the latter, falling through the channels in the working piston 8, made in the form of a half-piston, rigidly fastened together on a conical surface, acts on the ends of the half-sleeves 4 interconnected by dowels 5. In this case, half-sleeves 4, safety rings 6, rubber sealing rings 7 and spool sleeve 3 move upward with high speed. When the barrel 1 is thickened with half-sleeves 4, the last safety rings 6 and rubber o-rings 7 stop, and the spool sleeve 3 continues to move further by inertia until it locks with the conical surface of cylinder 2. A radial hole 15 made on spool sleeve 3, allows you to increase the fixation of the latter.

The proposed technical solution significantly increases the reliability of the centralizer by installing a spool sleeve in the cylinder, which allows to increase the strength of the centralizer during hydraulic fracturing of the reservoir.

Claims (3)

1. The hydromechanical centralizer, including a cylinder connected to the barrel, in the cavity of which bushings and a working piston are mounted, fixed relative to the cylinder by a shear pin, a spool sleeve, centering levers, lower ends pivotally connected to the barrel, locking devices, characterized in that there are 3 bushings pieces are made in the form of half-sleeves, interconnected in pairs with dowels, locking devices are made in the form of T-grooves on the bottom of the working piston, interacting with T-shaped pins, rigidly fastened to the centering levers, the spool sleeve is installed in the cylinder cavity above the half-bushings, the outer diameter of the sleeve being smaller than the inner diameter of the cylinder, the outer surface of the lower part of the working piston made in the form of a cone for interacting with the conical surface of the centering levers made on their upper part, and the working the piston is made in the form of a half-piston, rigidly fastened together in a conical part, a radial hole with a thread is made in the barrel, connecting the internal the cylinder bore and the barrel into which the destructible plug is screwed. 2. The hydromechanical centralizer according to claim 1, characterized in that the upper part of the inner cavity of the cylinder is made in the form of a cone for interaction with the outer conical surface of the spool sleeve, the latter having a radial hole made below the conical surface. 3. The hydromechanical centralizer according to claim 1, characterized in that the outer diameter of the barrel in the upper part under the spool sleeve is larger than the outer diameter of its lower part, and the radial hole is arranged to overlap with the spool sleeve after the centralizer is activated.

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